Edit in JSFiddle

var output = document.getElementById("o");

var callbacks = [];

for (var i = 0; i < 2; i++) {
    (function(_i) {
        callbacks.push(function() {
            return _i;
        });
    })(i);
}

for (var x = 0; x < callbacks.length; x++) {
    output.innerHTML += callbacks[x]();
}

<output id="o"></output>